1. Field of the Invention
This ivention pertains to the preparation of extra-wide nonwoven sheets. More particularly, the invention pertains to a process for preparing extra-wide, heat-sealed nonwoven sheets of thermoplastic synthetic polymer monofilaments.
2. Description of the Prior Art
Nonwoven sheets are prepared in general by spinning continuous monofilaments of spinnable thermoplastic synthetic polymers, drawing the freshly spun filaments to improve the tensile strength of the filaments, and depositing them on a collecting surface. The mats or batts of the intermingled monofilaments on the collecting surface are bound, for example, by heat sealing in an arrangement of heating and pressing rollers, belts, etc. See, for instance U.S. Pat. No. 3,630,816, the disclosure of which is hereby incorporated by reference.
The heat-sealed nonwoven sheets of thermoplastic synthetic polymer monofilaments are highly suitable as carpet backing. See, for instance, U.S. Pat. No. 3,360,421. However, heat-sealing machines are limited in width because of practical limitations on the size of heating and pressing rollers, belts, etc. Also, the close tolerances required in such heating and pressing operations make it difficult to work with large-size surfaces. Attempts to piece smaller sheets together to form extra-wide sheets are unsatisfactory, because of the problem of seams.
For these reasons the production of continuous extrawide nonwoven sheets has been a problem in the art.